When establishing a telecommunication connection, it is necessary to match the devices at both ends of an analog telecommunication connection. The devices are matched to each other with regard to their impedances and to the conductive properties of the telecommunication connection itself. This allows, for example, suppression of the formation of a speech echo such that it does not create a disturbance when operating the connection. This matching takes place in a known manner in that for different groups of line impedances, input impedances and balancing impedances a number of splitters and filters were developed that are used according to requirements. Additionally, matching the different conductive properties by reflecting incoming frequencies is also known, with the phase shift and amplitude attenuation being changed to achieve the required matching. With this variation, the property of reflection of frequencies with regard to amplitude attenuation and phase shift can be laid down in a simple manner in a coefficient table so that a variable matching to the different conditions of an analog telecommunication connection is obtained.
For all adjusting variations known according to prior art, it is necessary to calibrate the specific line or to give certain requirements for a specific line and in this way achieve a matching of the impedance of the exchange end. From a personnel point of view, this is very expensive on the one hand and, on the other hand, it is also not sufficiently flexible because by changing the environmental conditions, or also even more frequently changing the connection situation at the subscriber end, which cannot necessarily be influenced from the exchange end, changes in the situation over time result to which the network operator must adapt as quickly as possible.